Sound translation



March 29, 1932.

J. ENGL SOUND TRANSLATION Filed 001,-. 2, 1929 INVENTOR fisef'Z/lgZ ATTORNEYS i mated 29, 1932 f Its-1,164

, aosnrmet w- BER i WNEWA b,i i hlYh A S GNOKF n i'qi 'rimbiicrsgdb fi .ldiid speaker or other sonnd aniplifier con- "nected: thereto-,1hy continnous hissing and biizzing noises"which-are jcai1sed partly by sihall scratching OnQthe' strip and 'p artly by fluctuating electrostatic influences which 7 inSuIatOLiin I IiOYing' past the} photo electric cell or lother parts of the :electrical circuits 7 Allso, "the disturbing noises maybe caused by the small current flu'ctfia'tions which? are always presentfin electrical aniplifieifsTand ther "devices" which Bare supplied from an ontsidesonrceof ciirrent'fi f The object this invention is to pretent tible in the loudspeaker or other. sound; 're' producer, by meanso f the insertion of aslowpass? electric filtBii LCiI'QII it betweenthephotoelectric cell andthe'londfspeakerg ThQ'IfiltBI' V circuit is"so,dimensionedthat:the'alternating are notfallowed to pass as; far as theij'loud speake It has provenitobe'thecase that a 55" l0;0,00 per secon is generally adiiantageous Another pb 'ectjofgthefinvention i=5 to adapt anf aniplifying;"system :niore 1oarticidla'rlyZ to a "m iag rrfie em ms an ;-.c mbiee i ir *o i parts as maybe illustratedhnd described selves in such "sound reproduction" in ithe are produced by therecord film, .whichis an cellin which thereis produced; by means of L siich disturbing noises froni becoiniing percep battery; isfshojWn fas connected with the lower end of the potentiometer Aconplingiccapace ity 'Z:together withalead wire 8 connectithe l cell circuit with afiltericircuit 9.: This filter; v I in the; neighborhood "15f 85000 to r 'quencies. .c r

r e -210mm; EW: YORK in eonn'ectioni with theappziratus herein dis= closedby Way ofexampleonly and as illus trative of" certain preferred embodiments,

In the drawings, Fig. 1 shows diagrammatically as one example, an arrangement of the I filter system I etween the .photo e'lectric'icell andfthe loud-speaker; i. I Fig. 2 illustrates '-hOW a filter system may he arranged betweenrtwo successive stages ofa'multistage amplifier; and

-'Fig .'3- shows anexample of the' ifilter sy tein inserted between the last amplifier tube of: a multi-stageamplifier and-hithe 1 1 speakeri a. In Fig, 1, l represents the photo-electric illumination Whichvaries in conformityclw'ith the blackenings on'the film F,-a vYiLI'ifiblfilC I trlc current whose intensity corresponds to the' degree'o-fblackening uponwthefilm istrip V circuitmay consist of several fparallelecsk pa'cit1es-10, 10, and selffinductances :11; 111?; 1

- The sizes of the capacities and self-induc tances of the filter are chosen in suchaa. way that, starting from the desired-predetermined frequency limit, the.-. filter hasja erylihigh impedance and accordingly: becomes 'pract-ically 1 non-conducting for 1 all 1 higher lfre- I Theoutput terminals l2and 13 fftii mar lead to the cathode and grid of-the first'am:

plifier' tube 14'. Betweenthe cathode and grid -65 of this tubeithereare connected; theresistance 15"and the gridbifas battery 16. fE'Tc the firstj I amplifierQtube there is connectediy-in'fwell'u known "manner a second "stage of aniphficaf- 18 is connected. The tubes 14 and 17 may be suitably energied by A batteries, not shown, and by the batter 6 through reactances 19 and 20, respective? In Fig. 2 the filter system is connected between two successive stages of a multistage amplifier which may be connected to a hoto-electric cell as shown in Fig. 1. It will e understood that the connections shown in 2 may be substituted'for those shown to the ri ht o! the dot and dash line of Fig. 1. Also t e connections shown in Fig. 3 hereinafter described may similarly be substituted in Fig. 1. As shown, the filter circuit is located between the second from the last tube 21 and the last tube 22. To the amplifier tube 21 there is connected across a resistance 23, the positive. pole of a battery 24, whose negative pole is connected with the cathode of the tube 21. The lead wires 25 and 26 conduct the output potential of the tube 21 to the filter circuit 27, which is constructed in a manner similar to the filter in Fig. 1. The lead wire 28. .isconnected to the coupling capacity 29 and the lead wire 30 is connected to the tube 22 for the purpose of influencing the grid potential thereof. Between the cathode and thegrid there is connected a resistance 31 and the grid bias battery 32. The loud speaker 33 is mnnected to the output connections of tube 22 in any well known manner.

This hook-up has various advantages in comparison with that of Fig. 1. In the first place not only the frequencies coming from the photo-electric cell above the predetermined, frequenc limit are filtered out, but also. all those w 'ch ori inate from the sucs of appli cation with the excaption of t e last are eliminated. Furtherflore the impedance of the filter at a freeqmney above the predetermined frequency limit is considerably greater than that of the rallel resistance 31. This resistance hing adapted to the impedanceof the tube can appreciabl smaller than the parallel resistance 15 of e first tube, 14 in Fig. 1. On thisacconnt it is advantageous to connect the grid circuit of the final tube 22 with the filtercircuit, since the latter is less sensitive than the 'd circuit of the first tube illustratcd in ig. 1 and fluctuations therein prodmce lesstotal effect.

A third example of the invention is illustratcd in Fi 3. In this case 41 is the last tube of a m ti-stage amplifier which is conmeted through a resistance 42, with a positive le of a battery 43, the negative pole of w 'ch is connected to the cathode of the tube 41. The output of a photo-electric cell is; shown in Fig. 1 may be connected to the input connections of tube 41. The fluctuatiunaof potential of audio-frequency which have been amplified by the preceding tubes am conducted tethe grid of this tube. The lead "wires 44 and 45 conduct the fluctuations stable and of potential produced in the tube 41 to a filter circuit 46. In the lead wire 45 there is inserted a polarization battery 48 which supplies the polarization otential for a loud speaker 47, which is pre erably of the electrostatic t pe.

It i8 118 apparent that fildieht dily advantages resulting from this arrangement particularly in connection with the use 0 electrostatic telephones slid loud since eliietlostitie loud are more intenselgtgnfluenced by high frequencies than 'electr agnetic or other types of loud speakers.. Also the amplifiers are rendered more (#:iiet in operation.

It is furt er apparent that an efigcientarrangement is provided for eliminatingelectrostatic disturbance arising from frictional forces applied to the insulating rapidl moving film in passing throu h the repro g apparatus. The lOW-{RSS%lt81 arra 1 above described are particularly apteble for eliminating these disturbances, since the larger part thereof are of high fr uencies.

In my copendi application 1. No- 404,496, filed Novem r 2, 1929, covering divisional subject matter, certain electrical con nections for a photoelectric cell in sound reproduction apparatus are claimed and imclosed in detail.

While the invention has been described in detail with respect to certain articular preferred examples which give S tisfactory s'ults, it will be understood by those skilled in the art that various chan and modifications maybe made wi ut eparting the spirit and scope of e invention, it is intended therefore, to cover all such changes and modifications in the appended claims Whatl desire to claim is:

1. In a system for 'reproducingso'u'nd from ligtllxt sonn records utilizing a mgving ins tlng drip, a loudspeaker,

a light responsive cell, means f sai cell including a common high 50' source otpower, and a filter arra H .to pass currents having frequencies n the neighborhood of fmin 8,000 to 10,0 second and below, cdnsisting of was inductances and parallel capacltiespsaid loud speaker being of the electrostatic 'ty'p'a'an'd I connected to the filter in such a way as to be ene r ed b said potential thro h raidiniiuctances.

2. a s stem for reproducing sound light soun records, a li ht responsive "c d arr d to be aifected y a sound on a a plurality of resistance sliccessive coupled a Iifiers for amplifying the etfiicts of the current variations in said. light cell, a resistance connected i" iit of each amplifier, the resistance 'of the bei less than that ofthefirst, aloud spe er connected to receiveth'e amplified currents, and a'low vfpass filter arranged be- I tween two of said amplifiers.

on a film, a plurality of. resistance succes: sively coupled amplifiers for amplifying the 'efiectspf the current Variations in said light cell a resistance connected across the lnput 3 of each amplifier, theresistance ofthe' last being less thanth'at'of the first, a loud speaker connectedfto receive the amplified currents, and alow-pass'filter arranged bef tween the last two amplifiers,-the reactance "dig/of the filter being greater With'respect to W the resistance of the last amplifier than w vith respect to the resistance of the first or subsequent amplifiers.

In testimony whereof I have signed my nameto this specification.

JOSEF ENGL. A q 

